1. Field of the Invention
The present invention relates in general to semiconductor memory. In particular, the present invention relates to peripheral circuitry for high-speed receivers connected to high I/O voltages.
2. Description of the Related Art
An input-output (I/O) signal to a semiconductor device is usually a small amplitude signal within a large DC voltage range. In order to accommodate the high DC voltage, thick oxide devices are used. The receiving circuits comprising thick oxide devices to form amplifying stages, have limited performance because of large gate and junction capacitances. The receiving circuits comprising thin oxide devices to form amplifying stages and process high voltage I/O signals, are complicated circuits requiring special circuit techniques to ensure that the thin oxide devices avoid high voltage stress. Receiving circuits that transform signals from a high I/O voltage (VDDQ) to a low core (internal circuit) voltage (VDD) cause large delay skew between the rising and falling edges as VDDQ and VDD are independent.
U.S. Pat. No. 6,275,094 discloses a device to shift the threshold voltage in a receiver, which has both thick and thin oxide regions. The circuitry of the receiver contains a plurality of inverters and two feedback paths. U.S. Pat. No. 6,181,193 discloses a high voltage tolerant CMOS input and output interface circuit. A receiving circuit comprises a thick oxide CMOS with dual gate devices in a receiver and a driver. U.S. Pat. No. 5,911,104 discloses a chip design having thick and thin oxide and forms both bipolar transistors and DMOS transistors on the same chip. A high radio frequency receiver circuit is discussed which creates high voltage control signals. U.S. Pat. No. 5,786,618 discloses a high voltage charge pump and receiver on a dual gate oxide substrate. An N-isolation buried layer underlying high density and low voltage transistors define islands of arbitrary voltage on a substrate allowing the resulting circuits to operate at high voltage relative to the substrate.